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StatusCode

StatusCode is a 32-bit structured integer that signals the outcome of any OPC UA operation. It encodes both the high-level outcome and the specific reason code drawn from the OPC UA status table.

Field Meaning
Severity Good, Uncertain, Bad
Sub-code The specific status within the severity — e.g. BadTimeout, UncertainSensorNotAccurate
Info bits Optional flags layered on top, e.g. SemanticsChanged, StructureChanged

See Part 4 — Services, §7 StatusCodes for a list off all OPC UA standart defined status code values.

In o6\Python

StatusCode is a Python enum.IntFlag — every symbolic value from the OPC UA status table is a member of the enum, spelled in upper snake case (BadNodeIdUnknown becomes BAD_NODE_ID_UNKNOWN), and the underlying value is just the raw 32-bit integer. That means the containment operator tests the severity directly, without masking by hand:

status = o6.StatusCode.BAD_NODE_ID_UNKNOWN

if o6.StatusCode.BAD in status:
    print("is bad")

Warning

Only the severity and the info bits are independent bit positions. Sub-codes are values, not flags, so OR-ing two of them together does not describe two problems — BAD_NODE_ID_UNKNOWN | BAD_ATTRIBUTE_ID_INVALID is simply BAD_ATTRIBUTE_ID_INVALID. Compare a sub-code with ==, and use in only for the severity.

A StatusCode whose underlying value is 0 is the spec's Good with no info bits set — that's what an unset DataValue.status returns, so a missing status field is implicitly Good.

See also